| About this Abstract |
| Meeting |
2025 TMS Annual Meeting & Exhibition
|
| Symposium
|
Environmentally Assisted Cracking: Theory and Practice
|
| Presentation Title |
The Role of pH in Corrosion Fatigue: Understanding how Alkaline and Acidic Environments Affect Corrosion Fatigue Crack Growth Rates in Aerospace Aluminum Alloys |
| Author(s) |
Gabby C. Montiel, Jenifer Locke |
| On-Site Speaker (Planned) |
Gabby C. Montiel |
| Abstract Scope |
AA2xxx (Al-Cu) alloys are less susceptible to corrosion fatigue (CF) than AA7xxx (Al-Zn) alloys. This research shows that AA7075-T6 has a slightly acidic crack tip pH, while AA2024-T8 is more alkaline when loading in 0.6M NaCl. As loading frequency increases, the crack tip pH becomes closer to bulk pH, which is near neutral, for both alloys. 2xxx Al alloys have secondary phase precipitates containing Cu that are anodic to the matrix and corrode to redeposit metallic Cu increasing cathodic reaction kinetics. If this phenomenon occurs inside a crack, it could explain the local crack tip pH becoming alkaline allowing stabilization of a passive film to inhibit CF. The initial findings support this theory and work is ongoing to quantify CF crack growth rates and crack tip pH for model alloys that vary copper and zinc content to understand the role of these strengthening precipitates and crack tip passivity. |
| Proceedings Inclusion? |
Planned: |